Metanephric adenomas are usually positive for WT1 (diffuse nuclear) and CD57 (diffuse cytoplasmic; shown here). They are usually negative for CK7. Papillary renal cell carcinomas are usually positive for CK7 and negative for WT1 and CD57. Case courtesy of: Dr. Abdul Haleem, Dept. of Pathology, King Abdul Aziz Hospital, Al-Ahsa, Saudi Arabia.